Geo-Energie Jura SA (GEJ) has successfully completed the exploration phase of the Haute-Sorne (Canton Jura, Switzerland) geothermal pilot project. Tests conducted in July in the deep borehole confirm that rock permeability can be increased sufficiently to create a usable geothermal reservoir—while complying with the prescribed seismic thresholds. Geothermal energy is available around the clock, produces no CO₂ emissions, and is an ideal complement to other renewable energy sources.
The reassessment of seismic risk based on the current results is more favourable than the estimates that underpinned the 2015 project approval.
The first two reports on the tests carried out in the deep borehole were submitted to the authorities of the Canton of Jura yesterday; additional reports will follow in the coming months. These
documents will be reviewed from a safety perspective by independent experts appointed by the canton. On the basis of their professional assessments, the cantonal authorities will then decide on
the continuation of the project.
Beyond the continuation of the Haute-Sorne project, the positive results open up prospects for further geothermal initiatives in Switzerland. Geo-Energie Suisse (GES) plans to evaluate sites over the coming years for projects with an electrical capacity between 10 and 30 MW—ideally in combination with heat production.
Experience from comparable projects abroad shows that levelised electricity generation costs of under 15 Rp./kWh are realistic going forward. These economics improve further when power and heat production are combined.
Geothermal energy provides baseload-capable power that is available around the clock and produces no CO₂ emissions. For these reasons, geothermal electricity is an ideal complement to other renewable energies.
Conclusion
The positive results enable continuation of the review and approval process initiated by the cantonal authorities for the next project phase in Haute-Sorne.
Beyond Haute-Sorne, the findings open the door to developing new projects based on the multi-stage stimulation concept in both Switzerland and Europe. Larger projects and sites near major urban
centres are therefore moving further into focus.
Next steps
In Haute-Sorne, GEJ will provide the canton and the appointed experts with all required reports over the coming months to enable a complete review of the exploration phase. In parallel, Geo-Energie Suisse (GES) plans to evaluate sites in Switzerland for projects with an electrical capacity of 10–30 MW—ideally with concurrent heat production for medium to large district heating networks.
Prospects for industrialisation of future projects
As a reference, Fervo Energy’s “Cape” project (Utah) envisages around 500 MWe of geothermal capacity developed via more than 100 wells. The first 100 MW module is expected to come online in spring 2026; over 20 deep wells have already been completed. Thanks to technological advances in drilling in granite in the United States, wells there can be completed in about 20 days at a cost of roughly USD 5 million—around four times faster and less expensive than the Haute-Sorne exploration well. Even if technical conditions differ and not all U.S. technologies can be transferred one-to-one to Europe, the potential for large-scale cost reductions is substantial
Media contacts
Peter Meier — CEO, Geo-Energie Suisse AG — T +41 79 248 48 65 Olivier Zingg — CEO, Geo-Energie Jura SA — T +41 79 321 43 20 (out of office until 6 October)
| Geo-Energie Suisse AG is Switzerland’s centre of excellence for deep geothermal energy for power and heat generation. The company was founded in November 2010. Its founding members include municipal utilities and regional energy suppliers from across Switzerland (aet, EBL, ewz, EOS, ewb, GVM, iwb). Geo-Energie Suisse AG employs around 20 people and is supported on a project basis by external specialists. |
| Geo-Energie Jura SA was founded in 2015. Its shareholders are Geo-Energie Suisse AG, ebl, ewb and ewz. The company’s purpose is to implement and subsequently operate the Haute-Sorne geothermal project. Under a tripartite agreement concluded in June 2015 between the Municipality of Haute-Sorne, the Canton of Jura and Geo-Energie Suisse, the company is based in the Municipality of Haute-Sorne. |
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Stimulation test, July 2025 The exploration phase of the Haute-Sorne geothermal pilot project was concluded with the stimulation test in July 2025. The objective was to demonstrate that rock permeability can be increased sufficiently to create a usable geothermal reservoir—while complying with the prescribed seismic thresholds. Over the six-day test, a total of 430 m³ of water was injected at a depth of 3,800 m, with wellhead pressures of up to 270 bar. The microseismic response of the subsurface was recorded using seismometers installed directly in the borehole. The sensors’ close proximity to the stimulation zone enabled very high measurement sensitivity. In total, around 3,400 microseismic events were detected—providing an extensive dataset for assessing the seismic reactivity of the rock mass. |
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Key findings from the first two submitted reports
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More Information
http://www.seismo.ethz.ch/fr/monitoring/special-networks/geothermal-energy-haute-sorne/Monitoring/
https:// www.europeangeothermalcongress.eu/
https:// www.duglab.ethz.ch/en/home/
https:// www.fr.geo-energie.ch/2021/01/21/perc%C3%A9e-pour-la-g%C3%A9othermie-profonde/
https:// www.utahforge.com/
https://
www.utahforge.com/modeling-and-simulaon-forum-9-recording/
https://
www.fr.geo-energie.ch/g%C3%A9othermie-profonde/